Field of the Invention
The present invention relates to thermochromic color-memory composition and thermochromic color-memory microcapsule pigment encapsulating the same. More particularly, the present invention relates to: thermochromic color-memory composition which displays reversible discoloration between coloration and decoloration showing prominent hysteresis characteristics according to temperature change and retains either a colored state or a decolored state in an interchangeable and reversible manner even after removal of application of heat or cold required for the discoloration; and thermochromic color-memory microcapsule pigment encapsulating the composition.
Background Art
The present applicant has previously made proposals on thermochromic color-memory materials of this kind (see, for example, Patent Documents 1 to 6).
In contrast to reversibly thermochromic materials of a conventional type that change colors across a discoloration temperature, in which only one specific state of those states before and after the discoloration exits in a normal temperature range and the other state is maintained while heat or cold required for the expression of the specific state is being applied but the state in the normal temperature range is restored once the application of heat or cold is terminated, the above-mentioned thermochromic color-memory materials not only are capable of selectively maintaining either a color at the lower temperature side than the discoloration temperature or a color at the higher temperature side than the discoloration temperature in a normal temperature range but also can be made to interchangeably maintain these colors by applying thereto heat or cold as required, and such thermochromic color-memory materials have thus been applied to a wide variety of fields including the fields of thermochromic recording materials, toys and printing.